Process for the rapid processing of silver dye bleach material

ABSTRACT

The present invention relates to a rapid processing method of silver bleach materials. The bath sequence is: (1) silver developing bath, (2) dye bleach bath (3) bleach fixing bath, (4) silver halide fixing bath and (5) soaking bath. Baths (1) and (2) each contain dye bleach catalyst, the material passing from (1) directly into (2). The whole processing is carried out at temperatures of 20* to 50*C. The whole process lasts at most 6 minutes, the dwell time in the individual baths being at most 2 minutes.

United States Patent Marthaler et al.

[451 Feb. 25, 1975 PROCESS FOR THE RAPID PROCESSING OF SILVER DYE BLEACHMATERIAL Inventors: Max Marthaler, Marly-le-Petit;

Ulrich Frauchiger, Marly, both of Switzerland Assignee: Ciba-Geigy AG,Basle, Switzerland Filed: Feb. 16, 1973 Appl. No.: 333,249

Foreign Application Priority Data Feb. 28, 1972 Switzerland 2770/72 U.S.Cl. 96/53, 96/60 BF, 96/61 R Int. Cl. G03c 7/00, G03c 5/32, G03c 5/38Field of Search 96/53, 61 R, 60 BF, 20

References Cited UNITED STATES PATENTS 11/1964 Dreyfuss 96/53 3,394,0047/1968 Anderau et al. 96/53 Primary Examiner-David Klein AssistantExaminer-Richard L. Schilling Attorney, Agent, or Firm-Joseph G.Kolodny; Edward McC. Roberts; Prabodh l. Almaula [57] ABSTRACT Thepresent invention relates to a rapid processing method of silver bleachmaterials. The bath sequence is: (1) silver developing bath, (2) dyebleach bath (3) bleach fixing bath, (4) silver halide fixing bath and(5) soaking bath. Baths (1) and (2) each contain dye bleach catalyst,the material passing from (1) directly into (2). The whole processing iscarried out at temperatures of 20 to 50C. The whole process lasts atmost 6 minutes, the dwell time in the individual baths being at most 2minutes.

13 Claims, No Drawings PROCESS FOR THE RAPID PROCESSING OF SILVER DYEBLEACH MATERIAL 1n the modern photographic industry, the factor of timeplays an increasingly important role. An increase in the speed ofphotographic materials is desired in order to shorten the exposure time.The duration of wet processes is being shortened, or they are even beingreplaced by dry processes. The finishing of an image im mediately afterexposure is aimed at in copying establishments, and is also findingprogressively more acceptance in the practice of taking photographs.Materials, especially colour materials, for cameras which also performthe developing, or for automatic equipment, are therefore of topicalinterest. Such colour materials and processes for their development aredescribed, for example, in DT-OS 2,128,801, DT-AS 1,547,759 and DT-AS1,547,720. The colour images obtained according to these processes arehowever insufficiently stable to light, the colour reproduction isunsatisfactory or the manufacture of the material is expensive,

These disadvantages can be counteracted if a conventional silver dyebleach material is used as the colour material. However, it has nothitherto been possible to use the silver dye bleach material in therapid pro duction of colour images, because of the long treatment time,which is at least half an hour.

It is also known from the literature to process silver dye bleachmaterial in a ten-step process, DT-OS 1,472,811; DT-OS 1,924,723; E.Mutter, Farbphotographic Theorie and Praxis (Colour Photography inTheory and Practice), Springer Verlag (1967), page 57. It has also beendisclosed, from German Patent Specification No. 1,190,788, that the dyebleach catalyst can be added to the developing bath and that the dyebleach bath can contain small amounts of bleach catalyst.

According to the customary processing methods, the material is soakedafter the dye bleach bath, the metallic silver is oxidised in a silverbleach bath, the material is again soaked and the silver salts areeither converted into complexes which are insensitive to light(stabilisation process) or are eluted after conversion into watersolublecomplexes (fixing process).

It is also known to combine the silver bleach bath and the fixing bathin a bleach-fixing bath (compare Swiss Patent Specification No.336,257), of which the action time is determined by the slowest of thetwo processes, that is to say if the bleaching takes place slowly thegood fixing action is of no avail and conversely, if the fixing takesplace slowly, the good bleaching action is of no avail. Hence, therapidly acting bleach-fixing baths require the combination of a strongoxidising agent with a strong complex-forming agent. Such a combination,like the known Farmer's Reducer, is how ever not stable.

A rapid processing method which does not suffer from the abovementioneddisadvantages has now been discovered.

The process according to the invention for the rapid processing ofsilver dye bleach material, using the bath sequence (1) silverdeveloping bath, (2) dye bleach bath, (3) bleach-fixing bath, (4) silverhalide fixing bath and (5) soaking bath, with both the silver developing bath (1) and the dye bleach bath (2) containing a dye bleachcatalyst and the silver dye bleach material to be processed passing froma silver developing bath (1) directly into a dye bleach bath (2), ischaracterised in that the entire processing, from entry into the firstbath l to leaving the last bath (5) lasts at most 6 minutes attempeatures between 20 and 50C and that the dwell time in eachindividual bath is at most 2 minutes.

In the process according to the invention the acid dye bleach bath (2)follows, without intermediate soaking, onto an alkaline silverdeveloping bath l which is appropriately free of carbonates, theconcentration of the dye bleach catalyst in the silver developing bath(1) being so chosen, advantageously, that the loss in effectiveness ofthe dye bleach bath (2), caused by consumption and/or carrying over ofthe bath liquid, is reduced to a minimum. The catalyst concentration inthe silver developing bath is as a rule 10 percent to 300 percent higherthan the concentration in the dye bleach bath.

The bleach-fixing bath according to the invention, which preferably hasa pH value of at most 4 and contains an oxidising agent which iseffective in the acid bath, preferably a nitro compound, especially anitrobenzenesulphonic acid such as, for example,2,4-dinitrobenzenesulphonic acid, bleaches the silver very rapidly butis not capable of completing the fixing within the short time that itacts, so that, according to the invention, the material is additionallytreated with a silver halide fixing bath which appropriately contains,in addition to a relatively rapidly acting silver salt solvent, a highamount of sulphite, for example more than 20 g/l, to act as a bufferagainst acid carried into the bath and to render carried-over oxidisingagent harmless.

ln a preferred embodiment of the process according to the inventionthiourea is used as the silver salt solvent in the bleach-fixing bath(3).

In order to ensure that the processed material is completely stable, itis important to free the processed material completely of the bathcomponents which it carried with it. In a preferred embodiment of theprocess according to the invention this is done by allowing the materialfinally to pass through several soaking baths (5).

For better processing it is of advantage also to repeat all othertreatment stages (1) to (4), at least once.

If the number of available tanks and the time programme permit it, it isalso possible to employ soaking baths between baths having variouseffects, except between the silver developing baths (l) and the dyebleach baths (2).

All baths, including the soaking baths, can contain additives such ashardeners, wetting agents, optical brighteners and UV-protection agents.

The preferred processing temperature is between 30 and 40C.

The process according to the invention can be used,

for example, in the manufacture of positive colour imsists of paper feltthe latter must be lacquered, or coated with polyethylene, on bothsides. The lightsensitive layers are present on at least one side ofthis carrier, preferably in the known arrangement, that is to say ared-sensitised silver halide emulsion layer. which contains a cyan'azodyestuff, as the bottom layer, on top of this a green-sensitised silverhalide emulsion layer which contains a magenta azo dyestuff, anduppermost a blue-sensitive halide emulsion layer which contains a yellowazo dyestuff. The material can also contain base layers, intermediatelayers, filter layers and protective layers but the total thickness ofthe laycrs should as a rule not exceed 20 [.L.

Phenazines, quinoxalines and pyrazines can preferably be employed as dyebleach catalysts for the process according to the invention.

The concentration of the baths can be so adjusted, by simpleexperiments, that the dwell times in the individual baths are in theratio of small integers. Thus the ma terial can be processed in anautomatic developing machine which contains 5 to 20 tanks and where thedwell time per tank is to 30 seconds.

The bath system according to the invention has proved particularlystable to contamination by bath material being carried over, so thatconstant results are obtained even after processing major amounts ofexposed colour material.

Example 1 in the green-sensitive layer, above it, the magenta imagedyestuff of the formula IIO S and in the topmost bluesensitive layer,the yellow image dyestuff of the formula s out The image dyestuffs areincorporated into the emulsions at a reflectance density of D 2.0. Thecolour layers, containing a total of 0.8 g of Ag/m are sepa- 7 rated bygelatine layers, the total thickness being ,u..

This material is exposed by flashlight in a commercially availableautomatic portrait machine and is sub- Na metaborate g/l 40 seconds 40seconds 40 seconds tinoise Na bisulphite 10 g/l Passage time seconds 5times, soaking bath Passage time seconds CH: S Oall 280 seconds Totalprocessing time I 4 minutes 40 seconds) After drying by means of warmair, images having a good white, especially good white edge, and atrue-tonature reproduction, in colour and tonal values, of the personphotographed, are obtained. Even after the passage of 750 to 1,000images of passport photograph size, 4 cm X 5 cm, over the course of l0days, images of practically unchanged quality can still be produced.

Equally good results are obtained in the same tank installation iffinally only 4 soakings are carried out (total time of 4 minutesseconds); in this case the fourteenth tank is used to wash the holderused for transporting the material, and which is now empty. Less goodresults are obtained in accordance with the following methods of workingA and B which deviate from the process according to the invention.

A. The indicated procedure is followed but the developer solution doesnot contain a dye bleach catalyst. As a difference from Example 1, theconcentration of the dye bleach catalyst and the dye bleach bath israised from 80 mg/litre to 120 mg/litre. Whilst images developed infresh solutions show a white edge and usable quality in respect of skincolour and tonal values, the quality of the images progressivelydeteriorates on further use of the solutions. After about 750 imageshave been developed, sufficiently light images with a white edge can nolonger be produced even by adapting the exposure time. The effectivenessof the dye bleach bath has decreased so greatly that the dyestuffs areno longer bleached completely.

B. The process described in Example 1 is repeated. However, instead ofthe bleach-fixing bath according to the invention. a bath according toUS Pat. Specification No. 3,335,004 (Example 1), of the. followingcomposition, is employed:

Potassium ferricyanide 35 g/l Ammonium thiocyanate 90 g/l Potassiumbichromate 245 g/l Tertiary Nu phosphate 10 g/l The developed silver isonly oxidised insufficiently in this bleach-fixing bath. The imagesdeveloped in this way show an unattractive yellow-brown image edge.

Example 2 ln another type of automatic machine, only 10 tanks areavailable for processing; the dwell time is separately adjustable foreach tank.

The exposed material here passes through the same baths as in Example 1,but with the following processing sequence (temperature C):

Total processing time (6 minutes) The image quality and theutilisability of the solutions are as good as in Example 1.

360 seconds LII Equally good results are obtained if instead of usingthe dye bleach bath according to Example I a dye bleach bath of thefollowing composition is used:

Sulphuric acid, 96% strength 20 ml/l Thiomalic acid (mercaptosuecinicacid) I g/l Potassium iodide 20 g/l Catalyst:

2.3-Bis-(hydroxyntethyl)-6.7-dimethoxyquinoxalinc mg/l We claim:

1. Process for the rapid processing of silver dye bleach materials whichcomprises using the bath sequence (l silver developing bath, (2) dyebleach bath, (3) bleach-fixing bath, (4) silver halide fixing bath and(5) soaking bath, with both the silver developing bath (1) and the dyebleach bath (2) containing a dye bleach catalyst and the silver dyebleach material to be processed passing from a silver developing bath 1)directly into a dye bleach bath (2), the entire processing, from entryinto the first bath l to leaving the last bath (5) lasting at most 6minutes at temperatures of 20 to 50C and the dwell time in theindividual baths being at most 2 minutes.

2. Process according to claim 1, which comprises so chosing theconcentration of the dye bleach catalyst in the silver developing bath(1) that the loss in effectiveness caused by the consumption of catalystin the dye bleach bath (2) is minimized.

3. Process according to claim 2, which comprises using a bleach-fixingbath (3) with a pH value of at most 4 and containing an oxidising agentwhich is effective in an acid bath and using a silver halide fixing bath(4) that contains, in addition to a relatively rapidly acting silversalt solvent, more than 20 g/l of sulphite.

4. Process according to claim 3 which comprises using a nitro compoundas an oxidising agent.

5. Process according to claim 4 which comprises using anitrobenzenesulphonic acid as a nitro compound.

6. Process according to claim 3 which comprises using thiourea as thesilver salt solvent in the bleachfixing bath (3).

7. Process according to claim 1 which comprises di viding at least oneof the five baths into a plurality of units which are connected directlyone behind the other.

8. Process according to claim 7 which comprises using several silverdeveloping baths (1).

9. Process according to claim 7 which comprises using several dye bleachbaths (2).

10. Process according toclaim 7 which comprises using severalbleach-fixing baths (3).

11. Process according to claim 7 which comprises using several silverhalide fixing baths (4).

12. Process according to claim 7 which comprises using several soakingbaths (5).

13. Process according to claim 1, characterised in that the dwell timesin the individual baths are in the ratio of smaller integers.

l l l=

1. PROCESS FOR THE RAPID PROCESSING OF SILVER DYE BLEACH MATERIALS WHICHCOMPRISES USING THE BATH SEQUENCE (1) SILVER DEVELOPING BATH, (2) DYEBLEACH BATH, (3) BLEACH-FIXING BATH, (4) SILVER HALIDE FIXING BATH AND(5) SOAKING BATH, WITH BOTH THE SILVER DEVELOPING BATH (1) AND THE DYEBLEACH BATH (2) CONTAINING A DYE BLEACH CATALYST AND THE SILVER DYEBLEACH MATERIAL TO BE PROCESSED PASSING FROM A SILVER DEVELOPING BATH(1) DIRECTLY INTO A DYE BLEACH BATH (2), THE ENTIRE PROCESSING, FROMENTRY INTO THE FIRST BATH (1) TO LEAVING THE LAST BATH (5) LASTING ATMOST 6 MINUTES AT TEMPERATURES OF 20* TO 50*C AND THE DWELL TIME IN THEINDIVIDUAL BATHS AT MOST 2 MINUTES.
 2. Process according to claim 1,which comprises so chosing the concentration of the dye bleach catalystin the silver developing bath (1) that the loss in effectiveness causedby the consumption of catalyst in the dye bleach bath (2) is minimised.3. Process according to claim 2, which comprises using a bleach-fixingbath (3) with a pH value of at most 4 and containing an oxidising agentwhich is effective in an acid bath and using a silver halide fixing bath(4) that contains, in addition to a relatively rapidly acting silversalt solvent, more than 20 g/l of sulphite.
 4. Process according toclaim 3 which comprises using a nitro compound as an oxidising agent. 5.Process according to claim 4 which comprises using anitrobenzenesulphonic acid as a nitro compound.
 6. Process according toclaim 3 which comprises using thiourea as the silver salt solvent in thebleach-fixing bath (3).
 7. Process according to claim 1 which comprisesdividing at least one of the five baths into a plurality of units whichare connected directly one behind the other.
 8. Process according toclaim 7 which comprises using several silver developing baths (1). 9.Process according to claim 7 which comprises using several dye bleachbaths (2).
 10. Process according to claim 7 which comprises usingseveral bleach-fixing baths (3).
 11. Process according to claim 7 whichcomprises using several silver halide fixing baths (4).
 12. Processaccording to claim 7 which comprises using several soaking baths (5).13. Process according to claim 1, characterised in that the dwell timesin the individual baths are in the ratio of smaller integers.